Lighting systems

ABSTRACT

A lighting system may include one or more light sources and one or more light guides. A lighting system may be integrated into a window, a skylight, an exterior light such as a headlight, a tail light, or a high center-mounted stop light, or other exterior or interior portions of a system such as a vehicle. The light guide may be embedded in an adhesive layer in a vehicle structure. The light guide may be index-matched to the adhesive layer so that unilluminated portions of the light guide are indistinguishable from the vehicle structure. The light guide may be formed from optical fibers. The optical fibers may include a light-scattering optical fiber that scatters light out of the vehicle structure. The light-scattering optical fiber may be fused to a non-scattering optical fiber that guides light from a light source to the light-scattering optical fiber.

This application claims priority to provisional patent application No.62/397,076, filed Sep. 20, 2016, which is hereby incorporated byreference herein in its entirety.

FIELD

This relates generally to lighting systems and, more particularly, tolighting systems that can blend in with surrounding structures.

BACKGROUND

Systems such as vehicles generally have lighting systems. Lightingsystems in vehicles include interior lighting for providing aestheticlighting and informative visual output and exterior lighting such ashead lights and tail lights.

Existing lighting systems are generally visible to a user even when thelighting system is unilluminated. The visible presence of a lightingsystem in a vehicle may be aesthetically appealing or may prevent otherobjects from being visible through the lighting system.

SUMMARY

A lighting system may include one or more light sources and one or morelight guides. A lighting system may be integrated into a window, askylight, an exterior light such as a headlight, a tail light, or a highcenter-mounted stop light, a door panel, a dashboard, or other interioror exterior portions of a system such as a vehicle.

The light guide may be embedded in a polymer layer in a vehiclestructure. The light guide may be index-matched to the polymer layer sothat unilluminated portions of the light guide are transparent andindistinguishable from the vehicle structure.

The light guide may be formed from one or more optical fibers. Theoptical fibers may include a light-scattering optical fiber thatscatters light out of the vehicle structure towards the interior orexterior of the vehicle. The light-scattering optical fiber may be fusedto a non-scattering optical fiber that guides light from a light sourceto the light-scattering optical fiber.

Further features will be more apparent from the accompanying drawingsand the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a portion of an illustrative vehicle inaccordance with an embodiment.

FIG. 2 is a schematic diagram of an illustrative system with lighting inaccordance with an embodiment.

FIG. 3 is a front view of an illustrative illumination system having alight guide embedded in a vehicle structure in accordance with anembodiment.

FIG. 4 is a front view of the illumination system of FIG. 3 in anunilluminated state in accordance with an embodiment.

FIG. 5 is a cross-sectional side view of an illustrative illuminationsystem having a light guide embedded in a polymer layer in a vehiclestructure in accordance with an embodiment.

FIG. 6 is a cross-sectional side view of an illustrative light guidehaving a fiber core surrounded by cladding in accordance with anembodiment.

FIG. 7 is a cross-sectional side view of an illustrative light guidehaving a fiber core in accordance with an embodiment.

FIG. 8 is a cross-sectional side view of an illustrative light guideformed from a bundle of optical fibers in accordance with an embodiment.

FIG. 9 is a cross-sectional side view of an illustrative light guidehaving an optical fiber surrounded by a buffer layer with straight sidesin accordance with an embodiment.

FIG. 10 is a cross-sectional side view of an illustrative light guidehaving an optical fiber surrounded by a buffer layer with curved sidesin accordance with an embodiment.

FIG. 11 is a perspective view of illustrative light guides groupedtogether in a common buffer layer in accordance with an embodiment.

FIG. 12 is a front view of an illustrative illumination system having anon-scattering optical fiber that guides light to a light-scatteringoptical fiber with a reflective end in accordance with an embodiment.

FIG. 13 is a front view of an illustrative illumination system in whicha tapered portion of a first optical fiber is fused to a tapered portionof a second optical fiber to form an optical coupler in accordance withan embodiment.

FIG. 14 is a front view of an illustrative illumination system in whichan optical coupler is used to couple light from a non-scattering opticalfiber into a light-scattering optical fiber in accordance with anembodiment.

FIG. 15 is a front view of an illustrative vehicle structure havingmultiple illumination systems in accordance with an embodiment.

FIG. 16 is a front view of an illustrative vehicle structure having anillumination system with a light guide having multiple light-scatteringportions and multiple non-scattering portions in accordance with anembodiment.

FIG. 17 is a cross-sectional side view of an illustrative illuminationsystem having a light guide with a cleaved end to form a spotlight inaccordance with an embodiment.

FIG. 18 is a cross-sectional side view of an illustrative illuminationsystem having a light guide with a bulged end to form a spot light inaccordance with an embodiment.

DETAILED DESCRIPTION

An illustrative system of the type that may be provided withillumination is shown in FIG. 1. System 10 may be a vehicle, a kiosk, aroom in an office or other building, or other environment that includeslighting. Illustrative configurations in which system 10 is a vehiclemay sometimes be described herein as an example.

As shown in FIG. 1, system 10 may include windows such as front window12, rear window 14, side windows 16, and one or more top windows 18(e.g., a skylight) that are mounted in body 20. Body 20 may have doors30. The surfaces of doors 30 may sometimes be referred to as door panelsand face the interior of body 20. Dashboard 76 may be located in frontof seats 22. Buttons, dials, and other components may be provided ondashboard 76 and elsewhere in system 10 and may be provided withillumination from a lighting system. Footwells 80 may be covered withcarpeting or other suitable material.

Illumination may be provided in system 10 to illuminate the interior ofsystem 10 and/or to illuminate the exterior of system 10. As examples,interior lighting may be provided on windows of system 10 (e.g., frontwindow 12, rear window 14, skylight window 18, side windows 16, or othersuitable windows), the interior surface of doors 30 (e.g., on doorpanels), in footwells 80 (e.g., in the carpet or other material infootwells 80), on dashboard 76 (e.g., locations associated withinput-output components and/or other portions of dashboard 76), onhorizontal areas (seating surfaces) of seats 22, on the front of rear ofseatbacks in seats 22, on the front or rear of headrests on seats 22, ona headliner (e.g., on the interior of a vehicle roof), on interiorsurfaces of A pillars, B pillars, C pillars, or other structuralcomponents), on seatbelts, on a steering wheel, on an arm rest orconsole between seats 22, on an arm rest on doors 30, on mirrors, onrear seat footwells or other portions of the floor of system 10, or anyother interior surfaces of system 10.

Lighting may also be provided on the exterior of vehicle 10. Forexample, side mirrors may be formed on the left and right sides ofvehicle 10 and may include light-based output devices such aslight-emitting diodes. Vehicle 10 may also be provided with lights onthe rear of vehicle 10 such as rear lights 26 (e.g., turn signal lights,brake lights, tail lights, etc.). Rear lighting may also be provided onrear window 14 and/or other portions of the rear of vehicle 10. Therearward facing lighting of vehicle 10 may include center high mountedstop lamps (CHMSL) such as light 28. Light 28 may emit light throughrear window 14 or may be mounted on other rear portions of vehicle 10.Additional lights in vehicle 10 such as lights 24 may includeheadlights, turn signal lines, and fog lights. In general, lighting maybe provided on any interior and/or exterior surface of vehicle 10 suchas the roof of vehicle 10, the rear window or other rear surfaces ofvehicle 10, the front window or other front surface of vehicle 10, thedoors or other side surface of vehicle 10, protruding portions ofvehicle 10 such as mirrors or bumpers, or any other vehicle surface. Thelighting for vehicle 10 may be provided using light-based devices (lightsources) that have been mounted on the surface of vehicle 10 (e.g., onbody 20, inside a portion of body 20, in body 20 in an arrangement wherethe exterior of the light-based devices is flush with the surface ofbody 20, etc.) and/or using lighting that emits light through windows12, 14, 16, and/or 18.

FIG. 2 is a schematic diagram of an illustrative system with lighting.As shown in FIG. 2, system 10 may include control circuitry 34. Controlcircuitry 34 may include one or more microprocessors,application-specific integrated circuits, digital signal processors,microcontrollers, or other processing circuitry. Control circuitry 34may also include storage such as volatile and non-volatile memory, solidstate drives, hard disk drives, and removable storage media. Duringoperation of device 10, control circuitry 34 may process data and takesuitable actions in response. Data may be gathered from circuitry 34(e.g., clock information, status information on the current operatingstate of system 10, etc.) and may be gathered from input devices 36.Based on the data that is processed by control circuitry 34, controlcircuitry 34 may use electrical components such as output devices 38 totake actions such as displaying visual output for a user of system 10with a lighting system in devices 38, presenting audio output to theuser, adjusting an electromechanical actuator (e.g., to adjust steering,braking, etc.), controlling a motor (e.g., to position a seat), etc.

Input devices 36 may include force sensors. For example, devices 36 mayinclude force sensors based on strain gauges, force sensors based onpiezoelectric materials, force sensors based on compressible resistivefoam, capacitive force sensors (e.g., force sensors based on collapsiblefoam, fabric with conductive strands that serve as capacitiveelectrodes, or other capacitive force sensor structures), or other forcesensor structures that detect applied force such as applied force fromthe fingers (or other body part) of a user. Devices 36 may include oneor more proximity sensors that detect when a user's fingers (or otherbody part) or other external object is in the vicinity of the proximitysensor. The proximity sensors may include light-based proximity sensorsformed using light emitters (e.g., infrared light-emitting diodes) andcorresponding light detectors (e.g., infrared light detectors thatdetect infrared light from the infrared light-emitting diodes that havebeen reflected off of nearby objects), may include capacitive proximitysensors (e.g., sensors with capacitive proximity sensor electrodes thatmake capacitance measurements to detect when objects are nearby), may beacoustic proximity sensors, and/or may be other types of proximitysensors. Input devices 36 may also include touch sensors. The touchsensors may be based on acoustic touch technology, light-based touchtechnology, resistive touch, force-based touch, or other touchtechnologies. As an example, the touch sensor(s) may be capacitive touchsensors having capacitive touch sensor electrodes such as electrodesformed from strands of conductive material in a fabric, electrodesformed from strips of metal or other conductive material on dielectricsubstrates, or electrodes formed from conductive pads with otherconfigurations. Input devices 36 may also include environmental sensors(e.g., gas sensors, humidity sensors, temperature sensors, particulatesensors, etc.), keyboards and other devices with one or more keys orother buttons, accelerometers, magnetic sensors, compasses, pressuresensors (e.g., air pressure sensors and/or force sensors), touch sensorsin displays, microphones to gather voice commands and other audio input,and other input components.

Output devices 38 may include devices for presenting audio output (e.g.,speakers, tone generators, etc.), may include vibrators and other hapticdevices, and other components for presenting information to a user.Output devices 38 may also include light-based devices 32 for generatingvisible output. Light-based devices 32 may include displays (e.g., lightsources with arrays of individually controlled pixels such as liquidcrystal displays, organic light-emitting diode displays, projectordisplays, etc.), status indicator lights, and gauges to displaynavigation system information, media system information, vehicle statusinformation, and other information in the interior of vehicle 10.Light-based devices 32 may include external lighting for providinglight-based output outside of vehicle 10 (e.g., displays that emit lightexternally and/or other light sources that emit light in exterior areasof vehicle 10). In general, light-based devices 32 may include anysuitable light sources that produce light in response to appliedelectrical signals such as lamps, light-emitting diodes, plasma displaypanel pixels, illuminated status indicators, displays, lasers, arrays oflight sources, individual light sources, backlight units for displays,backlit or edge-lit light guides, light sources that emit one or morebeams of light (e.g., a laser beam, light-emitting diode beam, or a beamassociated with another collimated light source), light sources thatemit light in a fixed pattern of one or more beams, light sources thatemit light using raster scanning techniques, light sources that emitsteerable beams (e.g., light sources with mirror arrays to steer lightin a light projector system, light sources with one or more steerablemirrors, steerable lasers and light-emitting diodes, etc.), imageprojecting systems and other light projectors, light guide panels thatcontain light extraction features that cause the light guide panels toemit light in various patterns, and other electrically controlled lightsources.

Light-based devices 32 may contain individually controlled areas. Theseareas may be relatively small areas that serve as pixels in an array ofpixels for a display-type output device (e.g., a display integrated intoa dash-mounted navigation and media system or an external portion ofvehicle 10). Light-based devices 32 may also include components thatinclude one or only a few larger individually controlled areas (e.g.,one or more areas of about 1-100 cm², 10-1000 cm², 100-1,000,000 cm²,more than 1000 cm², less than 500 cm², etc.). For example, light-baseddevices 32 may contain light-producing devices that produce a singleblock of light over entire windows in vehicle 10 or other large areas ofvehicle 10. Individually controlled areas may be used to display fixedicons or other shapes, adjustable (e.g., customizable) icons or othershapes, fixed text (e.g., “stopping” to indicate the vehicle 10 isstopping, “road hazard ahead” to indicate that dangerous road conditionsare in the road ahead, “fog ahead” to indicate that there is fog in theroad ahead, “22 mph” to indicate that vehicle 10 is travelling at 22mph, “closing speed is 22 mph” to indicate that a vehicle followingvehicle 10 is closing in on vehicle 10 at a relative speed of 22 mph,etc.), customizable text, time-varying text, scrolling text, blinkingtext, and/or output of other shapes. The light output produced bylight-based devices 32 may have multiple adjustable attributes (e.g.,color, shape, intensity, duration, location, etc.) and any set of one ormore of these attributes may be used in conveying information to aviewer.

During operation, control circuitry 34 may generate control signals thatdirect a lighting system to generate output light (e.g., images, ambientlighting, lighting to adjust the aesthetic appearance of a structure insystem 10 by illuminating an interior surface of system 10 with adecorative pattern, virtual speedometers and other vehicle gauges, mediaplayback information panels and other information regions, exteriorillumination, etc.).

Light-based devices 32 may be based on light-emitting diodes, lasers, orother sources of light. In some configurations, light-based devices 32may be formed from light-emitting diodes or other light sources mountedadjacent to curved mirrors within clear plastic housings or othermounting structures (e.g., when forming headlights, etc.). If desired,light-based devices 32 may also have thin planar shapes (e.g., whenlight-based devices 32 are being mounted to windows 12, 14, 16, and/or18, or over relatively large surface areas on body 20 of vehicle 10).For example, light-based devices 32 may include flexible or rigidlight-emitting panels formed from edge-lit light guide films, organiclight-emitting diode substrates, backlit liquid crystal displays, orother planar light sources. Light-based devices 32 (e.g., light-emittingpanels or other light sources) may be opaque or transparent. Opaquestructures associated with light-based devices 32 may be used onportions of vehicle 10 such as opaque portions of body 20 or on portionsof windows 12, 14, 16, and/or 18 that can be obscured withoutinterfering with the fields of view of the occupants of vehicle 10.Transparent light-based devices 32 may be placed on transparent portionsof vehicle 10 such as portions of windows 12, 14, 16, and/or 18. Whennot emitting light, transparent devices will not block the views of theoccupants of vehicle 10.

Light-based devices 32 may, if desired, include light guiding structuressuch as optical fibers and/or other light guiding elements. Light guidesin devices 32 may be used to guide light from a light source to alocation in vehicle 10 where illumination is desired. Light guides indevices 32 may, in some arrangements, be transparent and may blend inwith a surrounding portion of vehicle 10 (e.g., to generate a uniformappearance). For example, light guides in devices 32 may be embedded inor attached to a transparent surface in vehicle 10 (e.g., a window, askylight, a transparent cover for an exterior light such as a headlight,a brake light, a tail light, etc., or other suitable transparent orsemi-transparent surface). The light guide may be index-matched to thesurrounding transparent structure and may therefore be invisible to thehuman eye when the light source is off (e.g., a user may be able to lookthrough the transparent structure without detecting the light guide orlight source) and/or when the light is propagating through anon-scattering portion of the light guide.

FIGS. 3 and 4 show an illustrative illumination system that blends inwith a surrounding structure in vehicle 10. In FIG. 3, illuminationsystem 32 is in an illuminated state (an “on” state), and in FIG. 4,illumination system 32 is in an unilluminated state (an “off” state).

Illumination system 32 may be incorporated into a portion of vehicle 10such as vehicle structure 40. Structure 40 may be a transparentstructure or an opaque structure. As an example, structure 40 may be atransparent structure such as a portion of a window (e.g., front window12, rear window 14, side window 16, skylight 18, or other suitablewindow), a transparent cover for an exterior light (e.g., headlight 24,tail light 26, a center high-mount stop light such as light 28, or othersuitable exterior light), a transparent cover for an interior surface ofvehicle 10, or other suitable transparent structure in vehicle 10.Arrangements where structure 40 is an opaque structure in vehicle 10(e.g., an opaque portion of body 20, dashboard 76, or other structure invehicle 10) may also be used. Structure 40 may be mounted to asurrounding support structure such as body 82 (e.g., a portion ofvehicle body 20 or other suitable support structure). Arrangements inwhich vehicle structure 40 is transparent are sometimes described hereinas an example. Illumination system 32 may be mounted on the inside oroutside of structure 40, may be embedded within structure 40, may bemounted on or embedded in an opaque body surface of vehicle 10, or maybe mounted elsewhere in vehicle 10.

As shown in FIG. 3, illumination system 32 may include a light sourcesuch as light source 56 and one or more light guides such as light guide42. In the example of FIG. 3, light source 56 is mounted to body 82 andlight guide 42 is mounted to vehicle structure 40. Illumination system32 may be used to supply ambient lighting, decorative lighting (e.g.,illuminated trim, surfaces with aesthetically pleasing decorativepatterns), exterior lighting (headlights, etc.), or other types ofillumination. Control circuitry 34 (FIG. 2) may issue control signals onpath 84 that determine the amount of light 44 that is emitted by lightsource 56. Light source 56 may be any suitable light source thatproduces light in response to applied electrical signals (e.g., one ormore light-emitting diodes, lasers, or other light sources).

As shown in FIG. 3, light-emitting diode 56 may emit light 44 into lightguide 42. Light guide 42 may be a fiber, a molded plastic structure, orother light guiding structure that guides light internally in accordancewith the principle of total internal reflection. Light guide 42 may beformed from clear plastic, glass, sapphire or other transparentcrystalline materials, or other transparent materials. In someconfigurations, light guides 42 may have inner structures (sometimesreferred to as cores) that are coated with one or more outer layers(sometimes referred to as claddings or coating layers). In this type ofarrangement, the core may have a higher index of refraction than thecladding to promote total internal reflection of the light that has beencoupled into light guide 42. High/low index of refraction arrangementsmay also be created by embedding a light guide structure of a firstindex of refraction into a transparent material of a second index ofrefraction that is higher than the first index of refraction. Thetransparent material into which the light guide structure is embeddedmay be a polymer or other clear binder.

In general, light guides 42 may be formed by injection molding, bymachining plastic light guide structures, by dipping or spraying polymercoatings onto machined or molded plastic core parts or glass core parts,by extruding polymers, by elongating glass or plastic rods using heatand tension, or by otherwise forming structures that can internallyguide light within vehicle structure 40 or other part of vehicle 10.With one suitable arrangement, which may sometimes be described hereinas an example, light guides 42 are formed from optical fibers. Thefibers may have circular cross-sectional shapes with central coressurrounded by cladding layers of lower index of refraction material. Thefibers may be formed form glass, plastic, or other transparent material.Arrangements in which light guides 42 have non-circular cross-sectionalshapes may also be used. In the example of FIGS. 3 and 4, fibers 42 areconfigured to emit light 44 at discrete locations across vehiclestructure 40.

Light guides such as light guide 42 may have one or morelight-scattering portions such as portion 42A and one or morenon-scattering portions such as portion 42B. In light-scatteringportions 42A, light guide 42 may have light extraction features such asparticles, changes in refractive index, roughened surfaces, protrusionssuch as bumps or ridges, recesses such as pits or grooves, or otherlight extraction features. In the presence of light extraction featuresin portion 42A of light guide 42, light 44 from the interior of lightguide 42 may be scattered out of light guide 42. For this reason,light-scattering portions 42A of light guide 42 may sometimes bereferred to as illuminable portions 42A (which may be illuminated orunilluminated depending on whether light source 56 is on or off). Innon-scattering portions of light guide 42 such as portion 42B, lightguide 42 may be free of light extraction features so that light 44propagates through and is contained within light guide 42 via totalinternal reflection. Because light does not escape from non-scatteringportions 42B, portions 42B may sometimes be referred to as unilluminatedportions 42B. If desired, light-scattering portions 42A andnon-scattering portions 42B may be joined via a fusion splice.

Light guides in illumination system 32 such as light guide 42 may, ifdesired, be transparent such that users are able to see through lightguide 42 when light guide 42 is unilluminated and/or when portions oflight guide 42 are unilluminated. Unilluminated portions of light guide42 (e.g., portions of light guide 42 where no light is present andportions in which light is present but not escaping from light guide 42)may therefore blend in with vehicle structure 40. As shown in theilluminated state FIG. 3, for example, non-scattering portion 42Bcontains light 44 within light guide 42 and blends in with thesurrounding portion of vehicle structure 40. Illuminated portion 42A, onthe other hand, scatters light 44 outwards (e.g., towards a passenger orother individual) and therefore stands out visibly from vehiclestructure 40.

In arrangements where vehicle structure 40 is opaque, unilluminatedportions of light guide 42 may blend in with the surrounding opaquematerial of structure 40. In arrangements where vehicle structure 40 istransparent, unilluminated portions of light guide 42 may blend in withthe surrounding transparent material of structure 40. With this type ofarrangement, light may pass through structure 40 and light guide 42.This may allow a driver or other occupant of vehicle 10 to look out ofvehicle 10 through structure 40 (e.g., through a window on whichillumination system 32 is mounted and through illumination system 32) tosee objects on the other side of vehicle structure 40.

If desired, light guide 42 may be index-matched with the surroundingmaterial of vehicle structure 40. With this type of arrangement, a userwill be unable to detect unilluminated portions of light guide 42 invehicle structure 40. For example, unilluminated portion 42B in FIG. 3may be undetectable to the human eye (e.g., may be indistinguishablefrom vehicle structure 40), even when portion 42A is illuminated.Illuminated portion 42A may therefore appear to be “floating” in themiddle of vehicle structure 40. In the off state of FIG. 4, the entiretyof light guide 42 may be unilluminated and may be invisible to a user(e.g., indistinguishable from vehicle structure 40), making vehiclestructure 40 appear completely clear and uniform.

In the example of FIGS. 3 and 4, light-scattering portion 42A of lightguide 42 forms a rectangle with rounded corners. Thus, when illuminatedwith light 44, an illuminated rectangle with rounded corners may appearto be “floating” in the middle of vehicle structure 40 sincenon-scattering portion 42B remains transparent and unilluminated evenwhen illumination system 32 is turned on. The shape of FIGS. 3 and 4 ismerely illustrative, however. If desired, illuminated portion 42A oflight guide 42 may form other illuminated shapes such as circles, ovals,parallel lines, triangles, text, symbols, and/or any other suitableshape or pattern. Arrangements in which multiple illuminated shapes areformed (e.g., separated from one another by non-illuminated regions 42B)may also be used.

FIG. 5 shows a cross-sectional side view of an illustrative illuminationsystem having a light guide of the type shown in FIGS. 3 and 4. In theexample of FIG. 5, vehicle structure 40 is a laminated structureincluding first and second layers 46 and 48 that are laminated togetherwith a polymer layer such as polymer layer 50. Layers 46 and 48 may beformed from glass, sapphire, diamond-like materials, plastics such aspolycarbonate, or other clear materials. Polymer layer 50 may be anoptically clear adhesive such as polyvinyl butyral (PVB), ethylene-vinylacetate (EVA), polyurethane, other suitable resin or adhesive. In oneillustrative arrangement, which is sometimes described herein as anexample, vehicle structure 40 may be laminated safety glass. This is,however, merely illustrative. If desired, one or more of layers 46 and48 may be opaque or only partially transparent. In some arrangements,layer 46 (e.g., the layer that forms a “background” for illumination 44because light 44 is emitted away from layer 46) may be a matte material,an ultra-black material, a light-absorbing material, a light-reflectivematerial (e.g., a mirror), a light-scattering material, or othermaterial. Layers 46 and 48 need not be planar, as shown in the exampleof FIG. 5. If desired, one or more of layers 46 and 48 may be curved ormay have curved portions.

As shown in FIG. 5, light guide 42 may be embedded in polymer layer 50.In the example of FIG. 5, light guide 42 includes light-scatteringportion 42A that receives light 44 (e.g., directly from a light sourceor from a non-scattering portion of light guide 42) and guides light 44so that it propagates in direction 86 (e.g., parallel to the y-axis ofFIG. 5). In light-scattering portion 42A, light guide 42 may have lightextraction features 90 (e.g., a change in refractive index, roughenedsurfaces, protrusions such as bumps or ridges, recesses such as pits orgrooves, embedded particles, or other light extraction features) thatallow some of light 44 to escape in direction 88 (e.g., parallel to thez-axis of FIG. 5) towards viewer 54. In non-scattering portion 42B,light guide 42 may be free of light extraction features 90 so that light44 propagates in direction 86 without escaping light guide 42. Lightguide 42 may have a diameter D between 140 microns and 170 microns,between 150 microns and 200 microns, between 100 microns and 130microns, between 150 microns and 180 microns, less than 140 microns, orgreater than 140 microns.

In arrangements where illumination system 32 is an exterior lightingsystem, layer 46 may face the interior of vehicle 10 and layer 48 mayface the exterior of vehicle 10 so that light 44 is emitted away fromvehicle 10 towards viewer 54 (e.g., a viewer that is outside of vehicle10). In arrangements where illumination system 32 is an interiorlighting system, layer 46 may face the exterior of vehicle 10 and layer48 may face the interior of vehicle 10 so that light 44 is emittedtowards the interior of vehicle 10 towards viewer 54 (e.g., a viewerthat is inside of vehicle 10).

If desired, light guide 42 and polymer layer 50 may have matching ornearly matching indices of refraction. For example, the index ofrefraction of light guide 42 may be within 3% 5%, 10%, 15%, 20%, 30%, or40% of the index of refraction of polymer layer 50. In one illustrativeexample, polymer layer 50 may have an index of refraction of about 1.478and light guide 42 may have an index of refraction of about 1.43. Thisis merely illustrative, however. Polymer layer 50 and light guide 42 mayhave other indices of refraction, if desired. By matching or almostmatching the refractive index of light guide 42 to that of polymer layer50, unilluminated portions of light guide 42 may be invisible. Forexample, non-scattering portion 42B may be invisible to users (e.g.,indistinguishable from vehicle structure 40), and light-scatteringportion 42A may only be visible when illuminated.

FIGS. 6-11 show cross-sectional side views of illustrative light guidesthat may be used in illumination system 32. In the example of FIG. 6,light guide 42 is formed from an optical fiber having a core such ascore 70 that is surrounded by a protective layer such as cladding 72.Optical fiber 42 may have light-scattering features 90 along its length.Light-scattering features 90 may be formed at uniform discrete locationsalong the length of fiber 42, may be formed at pseudorandom discretelocations along the length of fiber 42, or may be formed continuouslyalong the length of fiber 42. Light-scattering features 90 may be formedfrom any suitable structures that locally defeat the total internalreflection within fiber 42 (e.g., pits, bumps, scratches or othergrooves, ridges, particles with a different refractive index, localchanges in fiber shape and/or diameter, changes in cladding materialand/or index of refraction, abrupt bends, etc.). In the presence oflight scattering features 90, light from light source 56 (FIG. 3) may bescattered outwards towards a user.

If desired, cladding 72 may be formed from the same material as polymerlayer 50 (FIG. 5). For example, cladding 72 and polymer layer 50 mayboth be formed from polyvinyl butyral (PVB), ethylene-vinyl acetate(EVA), polyurethane, other suitable resin or adhesive. By formingpolymer layer 50 and cladding 72 from the same material, the differencein refractive index between cladding 72 and polymer layer 50 will beminimized and unilluminated portions of fiber 42 will be undetectable invehicle structure 40. This is, however, merely illustrative. If desired,cladding 72 and polymer layer 50 may be formed from different materials.

If desired, fibers 42 may not include a cladding, as shown in theexample of FIG. 7. With this type of arrangement, light-scatteringfeatures 90 may be formed from a difference in refractive index betweencore 70 and polymer layer 50, or may be formed from pits, bumps,scratches or other grooves, ridges, particles with a differentrefractive index, local changes in fiber shape and/or diameter, abruptbends, etc.

FIG. 8 shows how light guide 42 may be formed from a bundle of opticalfiber cores 70.

Optical fiber cores 70 may be free of cladding, as shown in the exampleof FIG. 8, or some or all of fiber cores 70 may have cladding (e.g.,individual cladding the surrounds individual fiber cores 70 or acollective cladding that surrounds multiple fiber cores 70).

FIG. 9 shows how light guide 42 may include a buffer layer such asbuffer layer 74. Buffer layer 74 may be formed from fluoropolymer suchas, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, orother polymer material. If desired, buffer layer 74 may be formed fromthe same material as polymer layer 50. For example, buffer 74 andpolymer layer 50 may both be formed from polyvinyl butyral (PVB),ethylene-vinyl acetate (EVA), polyurethane, other suitable resin oradhesive. By forming polymer layer 50 and buffer 74 from the samematerial, the difference in refractive index between buffer 74 andpolymer layer 50 will be minimized and unilluminated portions of fiber42 will be undetectable in vehicle structure 40. This is, however,merely illustrative. If desired, buffer 74 and polymer layer 50 may beformed from different materials. Optical fiber cores 70 may includecladding 72, as shown in the example of FIG. 9, or fiber cores 70 may befree of cladding.

In the example of FIG. 9, buffer 74 has a rectangular cross-section.With this type of arrangement, the outer surfaces of buffer 74 may beused to help align fiber core 70 within polymer layer 50. For example,the light-emitting surface of optical fiber 70 may face surface 74A ofbuffer 74. When placing light guide 42 in polymer layer 50, thelight-emitting surface of core 70 may face a particular direction byorienting surface 74A of buffer 74 towards that direction in polymerlayer 50.

In the example of FIG. 10, buffer 74 has a curved outer surface such ascurved outer surface 74B. The shapes of FIGS. 9 and 10 are merelyillustrative, however. If desired, buffer 74 may have an ovalcross-section, a circular cross-section, a triangular cross-section, orany other suitable cross-sectional shape.

If desired, buffer 74 may surround multiple fibers 70. This type ofarrangement is shown in FIG. 11. As shown in FIG. 11, multiple fibers 70may be embedded in buffer 74. Fibers 70 may be parallel to one anotheror may have non-parallel orientations. With this type of arrangement,the outer surfaces of buffer 74 may be used to help align multiple fibercores 70 within polymer layer 50. For example, the light-emittingsurfaces of optical fibers 70 may face surface 74C of buffer 74. Whenplacing light guides 42 in polymer layer 50, the light-emitting surfacesof cores 70 may face a particular direction by orienting surface 74C ofbuffer 74 towards that direction in polymer layer 50.

The examples of FIGS. 6-11 in which light guides 42 have fiber coreswith cross-sectional shapes are merely illustrative. If desired, lightguides 42 may include fibers with non-circular cross-sectional shapes(e.g., rectangular, triangular, polygonal, oval, trilobal, or any othersuitable cross-sectional shape).

FIG. 12 shows an illustrative arrangement for illumination system 32 inwhich one end of light guide 42 has a reflective surface to increase thehomogeneity and light extraction efficiency of light guide 42. As shownin FIG. 12, light guide 42 includes light-scattering portion 42A thatallows some of light 44 to escape from light guide 42 and non-scatteringportion 42B that propagates light 44 while containing light 44 in lightguide 42. Non-scattering portion 42B may be coupled to scatteringportion 42A (e.g., via fusion splicing, mechanical splicing, or othercoupling methods).

One end of light guide 42 such as end 92 may receive light 44 from lightsource 56. The opposing end of light guide 42 such as end 94 may have areflective coating such as reflective coating 58. Reflective coating 58may be formed from metal such as gold, silver, chrome, aluminum, orother metal, or may be formed from any other reflective material. Anylight 44 that does not escape from scattering portion 42A of light guide42 on its first pass through scattering portion 42A may be reflected atcoating 58 so that it passes back through light-scattering portion 42A asecond time. Additional light 44 may escape from light guide 42 after itis reflected back from coating 58, thereby increasing the uniformity oflight from light guide 42 and improving light extraction efficiency.

FIG. 13 shows an example in which first and second fibers 42A and 42Bare optically coupled to produce a continuous illuminated loop. As shownin FIG. 13, fiber 42B may have opposing ends 102 and 104. End 102 oflight guide 42 may receive light 44 from light source 56A, and end 104of light guide 42 may receive light 44 from light source 56B. Fiber 42Amay a light-scattering fiber that form a continuous loop. Fiber 42B maybe a non-scattering fiber that couples light 44 into fiber 42A. Inparticular, fibers 42A and 42B may have portions that form an opticalcoupler such as optical coupler 62.

In the example of FIG. 13, optical coupler 62 is a fused biconicaltapered coupler that is formed from a tapered region of fiber 42A and atapered region of fiber 42B that are fused (e.g., melted) together alonglength L. This is merely illustrative, however. If desired, opticalcoupler 62 may be formed by twisting fiber 42A and 42B along length L,by tapering fiber 42A and 42B along length L without fusing the fiberstogether, etc.

In the tapered regions that form optical coupler 62, the respectivediameters of fibers 42A and 42B may be reduced relative to the rest offibers 42A and 42B. The reduced diameters of fibers 42A and 42B andtheir proximity to one another brings the centers of the two fiber corescloser together, causing light 44 from non-scattering fiber 42B toescape into light-scattering Fiber 42A. This light is then cycledthrough light-scattering fiber 42A. Because fiber 42A is a continuousloop, the extraction features in fiber 42A and the absence of breaks infiber 42A cause light 44 to escape from fiber 42A to form a continuousilluminated loop. Meanwhile, fiber 42B is free of light-scatteringfeatures, so that fiber 42B is unilluminated (and thus undetectable tousers) and the continuous illuminated loop formed by fiber 42A appearsto be “floating” in the middle of vehicle structure 40.

The example of FIG. 13 in which fiber 42A forms a rectangular loop withrounded corners is merely illustrative. If desired, fiber 42A may formother loop shapes (e.g., circles, ovals, triangles, other polygons,etc.) or may form non-loop shapes with end portions (e.g., a symbol,letter, word, a set of parallel lines, etc.). Also, the use of two lightsources to inject light into fiber 42B is merely illustrative. Ifdesired, fiber 42B may only receive light from one light source.Arrangements in which multiple fibers are used to form multiple opticalcouplers with light-scattering fiber 42A may also be used.

FIG. 14 shows an example in which a separate optical coupler such asoptical coupler 64 is used to couple light from non-scattering fiber 42Binto light-scattering fiber 42A. Optical coupler 64 may be a microoptics coupler (e.g., having one or more prisms, mirrors, and/or otheroptical elements to redirect light 44 from fiber 42B to fiber 42A), afused-fiber coupler (e.g., having two or more fiber cores that aremelted together to transmit light from one fiber core to another fibercore), a planar waveguide coupler, or other suitable type of opticalcoupler. In the example of FIG. 14, optical coupler 64 has two inputsreceiving light from fiber 42B and two outputs providing light to fiber42A. This is, however, merely illustrative. If desired, optical coupler64 may have more than two inputs, less than two inputs, more than twooutputs, less than two outputs, etc.

If desired, multiple light guides may form multiple illuminated shapeson one vehicle structure in vehicle 10, as shown in FIG. 15. In theexample of FIG. 15, four illumination systems 32 are provided on vehiclestructure 40. Each illumination system 32 includes a light source 56that emits light 44 into a non-scattering fiber 42B of light guide 42,which in turn guides light 44 to light-scattering fiber 42A of lightguide 42, where it escapes to form an illuminated shape on vehiclestructure 40. Because light 44 is guided to light-scattering fiber 42Awith a non-scattering fiber 42B, the illuminated shape formed by fiber42A may appear to be floating in vehicle structure 40. This is merelyillustrative, however. If desired, the entirety of light guide 42 may beilluminated (e.g., may be formed entirely from light-scattering fiber42A).

In configurations where fibers 42A and 42B are index-matched (or nearlyindex-matched) to polymer layer 50 in vehicle structure 40, a user maybe unable to see fibers 42A and 42B in vehicle structure 40. This allowsusers to see objects such as object 98 through vehicle structure 40 andthrough unilluminated portions of light guide 42. In other words,vehicle structure 40 may appear to be completely transparent whenillumination systems 32 are turned off.

If desired, each illumination system 32 in FIG. 15 may be independentlycontrolled (e.g., each illumination system may receive separate,independent control signals from control circuitry 34 of FIG. 2), orillumination systems 32 may be controlled as a single illuminationsystem that responds to one set of control signals. There may be feweror more than four illumination systems in vehicle structure 40. Theexample of FIG. 15 is merely illustrative.

Illuminable portions of light guide 42 may have any suitable shape(e.g., loop, spiral, text, symbols, parallel lines, zigzag lines,checker pattern, an array of one or more of these shapes, etc.). Asshown in FIG. 16, for example, light guide 42 may have a curvy shapethat starts at one edge of vehicle structure 40 and ends on an opposingedge of vehicle structure 40. Light guide 42 may have one, two, three,or more than three light-scattering fibers 42A and one, two, three, ormore than three non-scattering fibers 42B. In general, any suitablenumber and shape of light-scattering portions 42A and non-scatteringportions 42B may be used to form the desired illuminated shape or shapeson vehicle structure 40.

FIGS. 17 and 18 show examples in which light guide 42 provides morefocused illumination (e.g., to form a spotlight). In the example of FIG.17, light guide 42 has an angled end such as cleaved end 60 that helpsfocus light 44 towards area 66 (e.g., an area inside of vehicle 10 or anarea outside of vehicle 10). Cleaved end 60 may be reflective or mayhave a different index of refraction that causes light 44 to exit lightguide 42 towards area 66. The shape of cleaved end 60 may help collimatelight 44 to form a bright spot in area 66.

In the example of FIG. 18, light guide 42 has an enlarged end such asenlarged end 68. Enlarged end 68 may serve as a lens that helps focuslight 44 onto area 66. Enlarged end 68, may, if desired, be formed bymelting the end of fiber 42 so that the melted portion of fiber 42begins to fall into the curved shape of FIG. 18. The bulged shape of end68 helps to collimate light 44 to form a bright spot in area 66.

The foregoing is merely illustrative and various modifications can bemade by those skilled in the art without departing from the scope andspirit of the described embodiments. The foregoing embodiments may beimplemented individually or in any combination.

What is claimed is:
 1. An illumination system, comprising: first andsecond layers, wherein at least the first layer is transparent; apolymer layer interposed between the first and second layers, whereinthe polymer layer attaches the first layer to the second layer; anoptical fiber embedded in the polymer layer; and a light source thatemits light into the optical fiber, wherein the optical fiber has lightextraction features that cause the light to scatter outwards through thefirst layer.
 2. The illumination system defined in claim 1 wherein thefirst and second layers each comprise glass.
 3. The illumination systemdefined in claim 1 further comprising an additional optical fiber thatis free of light extraction features, wherein the additional opticalfiber guides the light from the light source to the optical fiber. 4.The illumination system defined in claim 3 wherein the optical fiber andthe additional optical fiber are fused together.
 5. The illuminationsystem defined in claim 3 wherein the additional optical fiber and thesecond layer are transparent and wherein objects on one side of theillumination system are viewable from an opposing side of theillumination system through the first layer, the polymer layer, theadditional optical fiber, and the second layer.
 6. The illuminationsystem defined in claim 3 wherein the optical fiber forms an illuminatedloop.
 7. The illumination system defined in claim 3 wherein the opticalfiber has a first tapered region and the additional optical fiber has asecond tapered region, wherein the first and second tapered regions arefused together to form an optical coupler that couples the light fromthe additional optical fiber into the optical fiber.
 8. The illuminationsystem defined in claim 3 wherein the optical fiber has a reflective endthat reflects the light back through the optical fiber.
 9. Theillumination system defined in claim 1 wherein the polymer layercomprises polyvinyl butyral.
 10. The illumination system defined inclaim 1 wherein the polymer layer has a first index of refraction,wherein the optical fiber has a second index of refraction, and whereinthe second index of refraction is within five percent of the first indexof refraction.
 11. A vehicle, comprising: a body; a window mounted inthe body; and an illumination system having a light guide embedded inthe window, wherein the light guide is indistinguishable from the windowwhen the illumination system is unilluminated.
 12. The vehicle definedin claim 11 wherein the light guide comprises first and second opticalfibers, wherein the illumination system comprises a light source thatemits light into the first optical fiber, wherein the first opticalfiber guides the light to the second optical fiber, and wherein thesecond optical fiber provides the light to an interior of the vehiclewhen the illumination system is illuminated.
 13. The vehicle defined inclaim 12 wherein the second optical fiber has light extraction featuresthat cause the light to escape the second optical fiber towards theinterior of the vehicle, and wherein the first optical fiber is free oflight extraction features.
 14. The vehicle defined in claim 13 whereinobjects outside of the vehicle are viewable through the window and thefirst optical fiber when the illumination system is illuminated.
 15. Avehicle, comprising: a body; a vehicle structure mounted to the body,wherein the vehicle structure comprises a layer of adhesive and atransparent layer; and an exterior lighting system mounted to the body,wherein the exterior lighting system comprises an optical fiber in thelayer of adhesive and wherein the optical fiber scatters light throughthe transparent layer to illuminate an exterior area of the vehicle. 16.The vehicle defined in claim 15 wherein the exterior lighting systemforms part of a light selected from the group consisting of: aheadlight, a tail light, and a center high-mounted stop light.
 17. Thevehicle defined in claim 15 wherein the layer of adhesive has a firstindex of refraction, wherein the optical fiber has a second index ofrefraction, and wherein the second index of refraction is within fivepercent of the first index of refraction.
 18. The vehicle defined inclaim 15 wherein the exterior lighting system comprises a light sourceand an additional optical fiber, wherein the additional optical fiber isfused to the optical fiber, and wherein the additional optical fiberguides light from the light source to the optical fiber.